激光选区熔化TC4合金工艺优化及退火处理对显微组织的影响研究

Optimization of Selective Laser Melting on TC4 Alloy and Effect of Annealing Treatment on Its Microstructure

激光选区熔化技术是制备复杂钛结构的重要加工方式,而热处理是必要的后处理手段。首先利用激光选区熔化设备打印TC4合金块体结构,以激光功率、扫描速度及扫描间距为优化对象,以致密度为优化目标开展正交试验,得到成形工艺参数对致密度的影响排序及最优工艺参数。然后对最优工艺参数下的成形样件分别进行消除应力退火处理与完全退火处理,发现消除应力退火前后组织改变较小,而完全退火热处理使微观组织从亚稳态的α′相转变成了α+β相稳定组织,这使拉伸试样在完全退火处理后抗拉强度与屈服强度都有所降低,而延伸率大幅提高。

Selective laser melting(SLM)is an important processing method for preparing complex titanium structures,while heat treatment is a necessary post-treatment method.Taking laser power,scanning speed and scanning distance as optimization objects,and density as optimization objective,the block structure of TC4 alloy was printed by SLM equipment and the orthogonal experiment was carried out to find out the influence order of forming process parameters on densification,then the optimal process parameter was obtain.Subsequently,the stress-relief annealing treatment and complete annealing treatment were carried out for the formed samples under the optimal process parameters.The result showed that the microstructure changes little after stress-relief annealing,while it changes from metastableα′phase to stableα+βphase after complete annealing,which makes the tensile strength and yield strength of tensile specimens decrease after complete annealing,but the elongation increased significantly.